Rig mats are used to form a base on which to support a drilling rig. The rig mats distribute the load of the rig and are particularly useful when the rig is on soft ground.
The present invention is concerned with a type of known rig mat that comprises a rectangular steel grid of wide flanged beams. The grid is formed by spaced apart, longitudinally extending beams connected to transversely extending cross beams welded thereto. The openings between the steel beams are filled in with thick wooden beams seated on the lower flanges.
The rig mats must support a lot of weight and the underlying ground is often not uniformly supportive. Therefore bending of the grid when loaded can be a problem.